E2F4

E2F4 is a member of the E2F family of transcription factors, which play a crucial role in cell cycle regulation. These proteins are involved in controlling the expression of genes essential for DNA replication and cell proliferation. E2F4 is known to bind to DNA and form complexes with other proteins, notably the retinoblastoma protein (Rb) and its related pocket proteins like p107 and p130. These complexes can act as transcriptional repressors, inhibiting the expression of genes required for cell cycle progression.

Unlike some other E2F family members that are primarily activated during specific phases of the cell cycle, E2F4 appears to be more constitutively expressed, meaning it is present throughout the cell cycle. Its function is often associated with maintaining cells in a quiescent or differentiated state. When E2F4 is sequestered by pocket proteins, it prevents the activation of target genes needed for S phase entry. The dissociation of pocket proteins from E2F complexes, often triggered by growth factor signaling, can release E2F4 and potentially lead to cell cycle progression, although its role in activation is less pronounced than its repressive function. Aberrant E2F4 activity has been implicated in various cancers, highlighting its importance in maintaining normal cellular homeostasis.